Double-biased movable contact assembly



Oct. 18, 1966 J. L. HAYDU 3,280,291

DOUBLE-*BIASED MOVABLE CONTACT ASSEMBLY Filed Feb. 5, 1965 2 Sheets-Sheet 1 INVENTOR JOHN L.HAYDU /5 Q S Wm ATTORNEY Oct. 18, 1966 J. L. HAYDU 3,280,291

DOUBLE-BIASED MOVABLE CONTACT ASSEMBLY Filed Feb. 5, 1965 2 Sheets-Sheet 2 INVENT JOHN L. HA U I %7 BY ATTORNEY United States Patent 3,280,291 DOUBLE-BASED MOVABLE CONTACT ASSEMBLY John L. Haydn, Milwaukee, Wis., assignor to Allen- Bradley Company, Milwaukee, Wis, a corporation of Wisconsin Filed Feb. 5, 1965, Ser. No. 430,633 7 Cla ms. (Cl. 200-166 This invention relates to a double-throw switch, and resides more particularly in a switch including a reciprocable carrier provided with a cage, a movable contact member in the cage, and a pair of bias means operable between the ends of the cage and opposite sides of the movable contact member.

A switch according to this invention is particularly useful in an auxiliary contact assembly for an electromagnetic switch, such an assembly being shown in US. Patent No. 3,134,869, issued May 26, 1964, to Leland E. Lawrence for Electromagnet Assembly With Interfitting Parts. In that assembly, there is an auxiliary switch comprising a contact carrier engaged by and movable in response to the main switch armature so that a movable auxiliary contact spanner on the carrier is moved into and out of engagement with a set of stationary auxiliary contacts in response to opening and closing of the main switch. The auxiliary switch can be made to operate in either normally open or normally closed fashion by varying the placement of the stationary contacts. In one case the auxiliary circuit will be closed when the main switch closes, and in the other it will be closed when the main switch opens.

In many cases it is desirable to have both normally open and normally closed operation so that one auxiliary circuit is completed when the main switch opens and another when it closes. With the present invention, this is accomplished by providing a novel double-throw auxiliary switch with two spaced pairs of stationary contacts alongside. A movable contact member carried by the auxiliary switch engages one pair of stationary contacts when the main switch is open and the other when it is closed. Two separate bias means operating in opposed fashion against the movable contact member provide centering and orienting action and proper contact force for either position.

A functionally similar contact structure is shown in US. Patent No. 2,585,824 to Noyes. -In the Noyes structure, however, there are two movable contact spanners and a single bias means that operates between them, and this presents several disadvantages. Two movable contact spanners occupy considerable space, at least if they are properly separated, and this necessitates increased spacing between the stationary contacts thus increasing the overall size of the assembly. If spacing is kept to a minimum, the allowable travel of the carrier is in effect reduced since the two contact spanners are relatively thick and neither can move very far in a cage without coming into engagement with the other or compressing the intermediately disposed spring to a solid form. This can present a serious problem in an auxiliary contact assembly where the travel of the carrier is controlled by the travel of the main switch armature which must have a considerable travel to insure an effective break of the line contacts. Further, movable contact spanners are relatively expensive and providing two can result in a significant cost increase for mass produced switches.

It is an object of this invention to provide a doublethrow switch including a single movable contact member adapted to be engageable with either of two stationary contacts.

It is another object of the invention to provide a switch including separate, opposing bias means for the movable contact member so that proper contact force is maintained whichever stationary contact is engaged.

It is a further object of the invention to provide a switch including a pair of retainers interposed between the bias means and movable contact which are guidingly engaged with the walls of the cage.

It is still another object of the invention to provide a structure including stop means to prevent either retainer from moving past the center of the cage.

It is a still further object of the invention to provide a switch in which each of the retainer members is engageable with the movable contact member to keep it in proper alignment and to prevent it from falling from the cage.

It is a still further object of the invention to provide a switch in which the movable contact member is split with its facing edges provided with notches that are in register to form apertures engageable with projections on the retainers to orient and hold the movable contact member in place.

It is still another object of the invention to provide a switch in which there are spring bias means and spring seats on the retainers and the carrier on which the springs are seated to be held in place in the cage.

It is still another object of the invention to provide a structure which has all the foregoing advantages and yet is relatively inexpensive and simple to construct and assemble.

Other objects and advantages will appear from the description to follow. In the description, reference is made to the accompanying drawings, forming a part hereof, in which, by way of illustration and not of limitation, a preferred embodiment of the invention is shown.

In the drawings:

FIG. 1 is a side view in elevation of an auxiliary contact structure, for an electromagnetic main switch, including a double-throw switch embodying the invention, with parts of the side wall broken away to show the contact carrier and movable contacts in a rest position,

FIG. 2 is a side view in elevation similar to FIG. 1, but showing the carrier and movable contacts in an actuated position,

FIG. 3 is an exploded view in perspective showing the contact carrier and the movable contact assembly of the switch structure of FIGS. 1 and 2,

FIG. 4 is a rear view in elevation of the housing of the structure with the contact carrier and movable contact assembly removed,

FIG. 5 is a front view in elevation of the housing showing the location of terminals,

FIG. 6 is a view in section of the complete structure taken through the plane 66 shown in FIG. 4,

FIG. 7 is an enlarged view in section of the complete structure taken through the plane 7-7 shown in FIG. 4, to more clearly show the movable contact assembly at the location of the cage in the contact carrier, and

FIG. 8 is a fragmentary view on an enlarged scale taken through the plane 88 shown in FIG. 7.

The auxiliary contact structure shown in the drawings includes a molded box-like housing, designated generally by the reference numeral 1, which is open at the back, the back being to the left as seen in FIGS. 1, 2, 6 and 7, and which is mounted on a cover member 2 of an electromagnetic main switch (not shown). The main switch armature, a portion of which is shown in the drawings and designated by the reference numeral 3, is in front of and vertically reciprocable past the open back of the housing 1. The main switch is not shown in the drawings since the operation and structure of such switches is well known and since the double-throw switch of this invention is useful in other applications, including any case in which a switch is to be activated by a reciprocable actuating member. This could include, for example, use in push button stations or in connection with relays of various types. Reference is again had to U.S. Patent No. 3,134,869 for a showing of an electromagnetic switch including an auxiliary contact assembly in which this invention is particularly useful.

The housing 1 has a front wall 4 as shown in FIG. 5 which is of rectangular outline and which has ridges that form a cross to separate four terminals from one another. The housing 1 also has a flat top 5, a fioor 6, and side Walls 7. Running vertically along the inside of the front wall 4, at about its center line is a curved groove or channel 8, which is clearly shown in FIGS. 4 and 7, as well as being indicated by dotted lines in FlGS. 1 and 2. A projection 9 extends forwardly from the channel 3 near its top to serve as a spring positioner, as will be described.

Two first or upper stationary contact terminals 10 are mounted near the top of the front Wall 4 and on opposite sides of the groove 3 by means of rivets 11. The terminals 10 extend into the housing 1 and are provided at their inner ends with upper stationary contacts 12. As seen in FIGS. 4 and 6, the rivets 11 are of hexagonal shape and are set in mating openings in the molded housing 1 to resist rotation; they are also quite deep and have threaded interiors to receive the shanks of terminal screws 13. The terminal screws 13 are provided at the front of the wall 4 for connecting the terminals 10 into a desired circuit.

Near the bottom of the front wall 4' is a second or lower pair of stationary contact terminals 14, also on opposite sides of the groove 8, which are mounted by rivets 15. The terminals 14 extend into the housing 1 and are provided with lower stationary contacts 16 and terminal screws 17.

A reciprocably movable contact carrier designated generally by the reference numeral 18 is pivotally mounted in the housing 1 by a pin 19 extending between the side walls 7. The carrier 18 is provided with quills 20 extending outwardly on either side of its body and the pin 19 passes therethrough to give the carrier 18 a maximum bearing area with the pin 19. The contact carrier 18 is formed of an insulating mate-rial, preferably nylon which can easily be injection molded to form the quills 20.

The carrier 18 has a rear portion 21, to the left as seen in FIGS. 1 and 2, which serves as a finger that extends out of the housing 1 to overhang and be engageable with the armature 3. A compression spring 22, seated at one end around the projection 9 and at its other end around a projection 23 formed on the carrier 13, operates to urge the carrier in a counterclockwise direction as seen in the drawings. A front portion 24 of the carrier 18 is in the housing 1 and extends into the groove 8 to be between the members of the pairs of upper and lower stationary contacts 12, 16.

As can be seen most clearly in FIG. 3, the carrier portion 24 has a rectangular aperture 25 therethrough that serves as a cage having opposite generally vertical side walls 26 and opposite upper and lower end walls 27. Both vertical edges of both walls 26 are notched to define four vertical guide channels 28. At about the midpoint of each channel 28 is a projection 23 which is actually an interruption in the channel 28 and serves as :a stop means to divide the channel 28, and, as will be discussed, the cage 25, into upper and lower parts.

Disposed within the cage 25, on opposite sides of the projection 29 and near opposite end walls 27 is a pair of retainers 30 formed of sheet metal. Each retainer 30 has four cars 31 turned toward the associated end wall 27 which are received in the channels 28. The retainers 30 are thus vertically slidably mounted in the cage 25 with the engagement of the ears 31 in the channels 28 serving to guide the sliding movement, the ears 31 and channels 28 together thus serving as guide means. The

cars 31 cannot move past the projections 29 which thus serve as stop means and serve to hold each retainer 30 in its half of the cage 25 and prevent it from moving past the center of the cage 25.

The opposite, outer surfaces of the retainers 30 are provided with central projections 32, and the facing end walls 27 are provided with central projections 33. A pair of spring bias means 34 are seated on the projections 32, 33 and operate between the end walls 27 and retainers 30 to urge the retainers 30 toward the center of the cage 25 and the projections 29.

Disposed between the facing surfaces of'the retainers 31 is a movable contact spanner 35 which has its central portion in the cage 25 and extends outwardly on both sides of the carrier 18, the spanner 35 being freely movable between the end walls 27. The movable contact spanner 35 is preferably of the two part or split type described more fully in the co-pending application of Leland E. Lawrence, Serial No. 390,271, filed August 14, 1964, and comprises two separate, parallel elements 35' which are substantially identical. This split construction is advantageous in that it ensures effective electrical contact in low voltage, cold circuit applications where particles of dust or the like might otherwise interfere with contact operation. With the split construction at least one of the two elements 35 is virtually certain to make a good contact and each is of sufiicient size to carry the full current load it necessary. It will be obvious, however, that a conventional one piece spanner could be used without departure from the invention.

Both the upper and lower surfaces of both ends of both members 35 are provided wit-h movable contacts 36. Since the elements 35' are ordinarily adjacent one another, being so held by the walls 26, adjacent members 36 operate together and the net elfect is that the spanner 35 is provided with four contacts, each comprising two members 36, there being upper and lower contacts on opposite sides of the carrier 18. When the carrier 18 is in the housing 1, the upper and lower contacts on each end of the spanner 35 are between and aligned with the corresponding upper and lower stationary contacts 12, 16.

The facing edges of the members 35 are provided on opposite sides of their midpoints wit-h facing, semi-circular notches 37. When the members 35 are together, the notches 37 are in register to provide a pair of vertical openings through the spanner 35 on opposite sides of its midpoint. The facing surfaces of the retainers 30 are each provided with a pair of projections 38 which mate with and are received in the openings formed by the notches 37, the openings and projections 38 serving as orienting means to orient and hold the spanner 35 in place as will be described.

When the spanner 35 is not in engagement with either set of stationary contacts 12, 16, the springs 34 move the retainers 30 to and against the stop means 29. In this position, the spanner 35 is held at the center of the cage 25 and is engaged by both retainers 30, the projections 38 of both being received in the openings formed by the notches 37, the spanner 35 thus being held against longitudinal and rotational movement. From this centered position, which is only transitory in normal use, the spanner 35 is free to be moved either upwardly or downwardly against a respective spring 34 and retainer 30. When such movement occurs, the other retainer 30 is held by its spring 34 against the projections 29 and does not interfere. The projections 38 of the retainers 30 against which the spanner 35 moves remain in engagement with the openings formed by the notches 37 so that the spanner 35 continues to be held against undesired movement.

The operation of the invention can be understood with reference to FIGS. 1, 2, 6 and 7. In FIGS. 1, 6 and 7 the carrier 18 is in its normal or rest position. That is, the armature 3 is down and the spring 22 has rotated the carrier 18 in a counterclockwise direction, this motion being limited by engagement of the carrier portion 24- with the underside of the portion of the groove 8 from which the projection 9 extends. moves the carrier 18, the upper movable contacts on the spanner 35 come into engagement with the upper stationary contacts 12 and the spanner 35 is thus stopped. The carrier 18 has an overtravel, however, and further rotation causes the spanner 35, in eifect, to be moved downwardly in the cage 25 against the lower spring 34 and retainer 30, the spring 34 thus providing a predetermined contact force. The relative translation of the spanner 35 and lower retainer 30, with the spanner 35 separating from the upper retainer 30, is clearly shown in FIG. 7.

When the armature 3 moves upwardly, the carrier 18 is rotated in a clockwise direction against the spring 22 to an actuated position shown in FIG. 2, this movement normally being limited by the upward extent of the travel of the armature 3. The lower spring 34 expands during the first phase of this movement until the lower retainer 30 strikes the stop projections 29, and then the contact spanner 35 is in its center position. The spanner 35 then disengages from the lower stationary contacts 16 and travels with the carrier 18 until it engages the upper stationary contacts 12. Again there is an overtravel, so that the spanner 35 is in effect moved relatively upward in the cage 25 against the upper spring 34 and retainer 30, to thus assume the position of FIG. 2.

Assuming that the switch armature 3 is normally in the position of FIG. 1, the upper contact terminals 10 and their contacts 12 can be included in a normally closed auxiliary circuit, While the lower terminals 14 and their contacts 16 are in a normally open circuit. When the main switch armature 3 then moves to the position of FIG. 2, the normally closed circuit opens and the normally open circuit closes.

To summarize, this invention comprises a double-throw switch including the pivotally reciprocable carrier 18 and the single movable contact member or spanner 35. There are opposing bias means, the springs 34, which act on opposite sides of the spanner 35 and serve to provide a predetermined contact force in both rest and actuated positions. The retainers 30 perform several important functions. The orienting projections 38 cooperate with the openings formed by the notches 37 to position the spanner 35 and hold it against longitudinal or rotational movement. The ears 31 cooperate with the channels 28 to guide the springs 34, and the engagement is such that the retainers 30 can pivot slightly to compensate for the pivotal movement of the carrier 18 and to insure that the spanner 35 is brought flat against the stationary contacts 12, 16, which are appropriately angled. The ears 31 also cooperate with the stops 29 to hold each retainer 30 and spring 34 in its half of the cage 25, thus preventing the spring 34 that is not being used from interfering with the other. The spring seats 32 operate with the seats 33 to hold the springs 34 in the cage 25.

Although a preferred embodiment of the invention has been shown and described herein, variations may be made without departure from the invention. Accordingly, the

As the spring 22 invention is not to be limited by the particular showing or description or in any other fashion except insofar as the claims appended hereto are to be interpreted.

I claim:

1. A double-biased movable contact assembly comprising: a reciprocally movable contact carrier having a cage with opposite, generally vertical side Walls provided with vertical channel means and opposite upper and lower end walls; a movable contact member disposed in the cage and extending outwardly therefrom that is vertically reciprocally movable between the end walls; a pair of retainers vertically movable disposed in the cage that are on opposite sides of and engageable with the movable contact member, each retainer being provided with ear means received in the channel means so that the retainer is guided in its vertical movement; and a pair of bias means, one bias means being disposed between each retainer and the nearest cage end wall to urge the associated retainer toward the center of the cage.

2. A contact assembly according to claim 1 wherein the movable contact member is freely movable past the mid-point of the cage; and wherein the channel means is interrupted to provide stop means near the midpoint of the cage and engageable with both retainers to prevent the retainers from moving past the midpoint of the cage.

3. A contact assembly according to claim 1 including cooperating orienting means on each retainer and the movable contact member to hold the movable contact member against movement out of the cage.

4. A contact assembly according to claim 1 wherein there is an aperture through the movable contact carrier that defines the cage; and wherein the movable contact member extends outwardly on both sides of the cage; and wherein both vertical edges of both side walls are cut away to define four channels comprising the channel means; and wherein each retainer is provided with four ears received in the channels.

5. A contact assembly according to claim 4 wherein the movable contact member is movable past the midpoint of the cage; and wherein each channel is interrupted near its midpoint, the interruptions comprising stop means engageable with the ears of both retainers to prevent the retainers from moving past the midpoint of the cage.

6. A contact assembly according to claim 5 including cooperating orienting means on each retainer and the movable contact member to hold the movable contact member against movement out of the cage.

7. A contact assembly according to claim 6 wherein the orienting means for each retainer and the movable contact member is operable at two spaced points whereby the movable contact member is also held against unlimited pivotal movement in a horizontal plane.

References Cited by the Examiner UNITED STATES PATENTS 8/ 1953 Schleicher 200-166 8/1965 Lemke 200-166 

1. A DOUBLE-BIASED MOVABLE CONTACT ASSEMBLY COMPRISING: A RECIPROCALLY MOVABLE CONTACT CARRIER HAVING A CAGE WITH OPPOSITE, GENERALLY VERTICAL SIDE WALLS PROVIDED WITH VERTICAL CHANNEL MEANS AND OPPOSITE UPPER AND LOWER END WALLS; A MOVABLE CONTACT MEMBER DISPOSED IN THE CAGE AND EXTENDING OUTWARDLY THEREFROM THAT IS VERTICALLY RECIPROCALLY MOVABLE BETWEEN THE END WALLS; A PAIR OF RETAINERS VERTICALLY MOVABLE DISPOSED IN THE CAGE THAT ARE ON OPPOSITE SIDES OF AND ENGAGEABLE WITH THE MOVABLE CONTACT MEMBERS, EACH RETAINER BEING PROVIDED WITH EAR MEANS RECEIVED IN THE CHANNEL MEANS SO THAT THE RETAINER IS GUIDED IN ITS VERTICAL MOVEMENT; AND A PAIR OF BIAS MEANS, ONE BIAS MEANS BEING DISPOSED BETWEEN EACH RETAINER AND THE NEAREST CAGE END WALL TO URGE THE ASSOCIATED RETAINER TOWARD THE CENTER OF THE CAGE. 